The SAM4s SPS-530 model R or F uses 3 1/8" thermal paper. because this cash register uses thermal paper there is no need for ink of course. Of course because this machine features a receipt printer only there is nothing else required. If your SPS-500 series has a receipt and journal it is a Model SPS-520 and requires different paper rolls. Keep paper in your register even if you don't issue a receipt on a regular basis. If you don't you could damage the machine and of course there is a sensor that won't allow it to operate without paper. If you use a kitchen printer or bar code printer with your register in most cases that will require a different type of paper.